Abstract

The role of sliding orientation on the tribological properties of polyethylene (PE) is investigated by using classical molecular dynamics simulations. Cross-linked PE surfaces slide against one another in two different directions: one that is perpendicular to and one that is parallel to the aligned direction of the polymer chains. The results indicate that sliding in the parallel direction occurs with a lower friction coefficient than sliding in the perpendicular direction. In both cases, gross level stick-slip motion is observed to be associated with the sliding of a restrained, corrugated molecular interface. In addition, the simulations demonstrate the way in which the system stores more shear strain energy during sliding in the perpendicular direction. The tribological behavior of these PE surfaces is compared to the behavior of similarly modeled polytetrafluoroethylene surfaces; the differences and similarities between the two systems are discussed.

Received 27 August 2007Accepted 28 January 2008Published online 16 April 2008

Acknowledgments:

The authors acknowledge the financial support of DARPA under USAF Contract No. FA8750-06-C-0050 and USAFOSR-MURI Grant No. FA9550-04-1-0367. The University of Florida High-Performance Computing Center is also acknowledged for providing computational resources and support.